// track revision number until propagation finishes
if len(d.State.PropagatingRevisions) == 0 {
d.State.PropagatingRevisions = make(map[string]*deploymentspb.PropagatingRevisions)
workflow.go
}
revs, ok := d.State.PropagatingRevisions[bld]
if !ok {
d.State.PropagatingRevisions[bld] = revs
}
revs.RevisionNumbers = append(revs.RevisionNumbers, revisionNumber)
}